1. Field of the Invention
The present invention relates to a printer, and a control method for the printer.
2. Description of Related Art
Japanese Patent Application Laid-Open Publication No. 2001-39546 discloses a prevailing control technique for printers including: providing an offset-stacking sheet discharge mechanism for discharging printed sheets to a stack position alternating between offset positions, and printing a plurality of copy sets; and controlling the stack position to alternate every copy set to thereby define sections of copy set stacks. For a current printing job following a previous printing job, it stores in memory a last stack position in the previous printing job, and determines a position offset from that position as an initial stack position in the current printing job. This permits sections of stack sets to be defined between the previous and current printing jobs, without confusion, when the current printing job is started without removing a set of copy-set stacks of the previous printing job from a stacker.
FIG. 1 illustrates a result of an offset stacking on a stacker. It shows a result of a printing job series including a sorting print job 1 for printing two copy sets each consisting of three pages, and a sorting print job 2 for printing two copy sets each consisting of four pages. As used herein, for a printer, the sorting print means a consecutive printing of a designated number of copy sets each consisting of a given number of pages sorted in order. In a non-sorting print, the printer makes a consecutive printing of copy sets corresponding in number to the given page number, the copy sets each consisting of non-sorted sheets (of a page) corresponding in number to the designated copy set number. Accordingly, the non-sorting print provides a total number of printed sheets identical to that of the sorting print.
As illustrated in the above figure, the job 1 provides a set of copy-set stacks including a first copy set consisting of pages sorted in order of a 1st, a 2nd, and a 3rd and stacked in a position at the left in the figure, and a second copy set consisting of pages sorted in order of a 1st, a 2nd, and a 3rd and stacked in a position at the right in the figure. This allows for defined stack sections of the first and second copy sets.
Then, the job 2 provides a first copy set consisting of pages sorted in order of a 1st, a 2nd, a 3rd, and a 4th and stacked in a position at the left in the figure. This is because the printer, which has stored in memory a last stack position of job 1 as the right, determines a position offset to the left from that position as an initial stack position in job 2. The job 2 further provides a second copy set consisting of pages sorted in order of a 1st, a 2nd, a 3rd, and a 4th and stacked in a position offset to the right in the figure. This allows for defined stack sections of the first and second copy sets, as well as for defined sections of stack sets of job 1 and job 2.